/*
 *  Copyright 2008-2013 NVIDIA Corporation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

/*! \file remove.h
 *  \brief Sequential implementations of remove functions.
 */

#pragma once

#include <thrust/detail/config.h>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header
#include <thrust/detail/function.h>
#include <thrust/system/detail/sequential/execution_policy.h>

THRUST_NAMESPACE_BEGIN
namespace system
{
namespace detail
{
namespace sequential
{

_CCCL_EXEC_CHECK_DISABLE
template <typename DerivedPolicy, typename ForwardIterator, typename Predicate>
_CCCL_HOST_DEVICE ForwardIterator
remove_if(sequential::execution_policy<DerivedPolicy>&, ForwardIterator first, ForwardIterator last, Predicate pred)
{
  // wrap pred
  thrust::detail::wrapped_function<Predicate, bool> wrapped_pred{pred};

  // advance iterators until wrapped_pred(*first) is true or we reach the end of input
  while (first != last && !wrapped_pred(*first))
  {
    ++first;
  }

  if (first == last)
  {
    return first;
  }

  // result always trails first
  ForwardIterator result = first;

  ++first;

  while (first != last)
  {
    if (!wrapped_pred(*first))
    {
      *result = *first;
      ++result;
    }
    ++first;
  }

  return result;
}

_CCCL_EXEC_CHECK_DISABLE
template <typename DerivedPolicy, typename ForwardIterator, typename InputIterator, typename Predicate>
_CCCL_HOST_DEVICE ForwardIterator remove_if(
  sequential::execution_policy<DerivedPolicy>&,
  ForwardIterator first,
  ForwardIterator last,
  InputIterator stencil,
  Predicate pred)
{
  // wrap pred
  thrust::detail::wrapped_function<Predicate, bool> wrapped_pred{pred};

  // advance iterators until wrapped_pred(*stencil) is true or we reach the end of input
  while (first != last && !wrapped_pred(*stencil))
  {
    ++first;
    ++stencil;
  }

  if (first == last)
  {
    return first;
  }

  // result always trails first
  ForwardIterator result = first;

  ++first;
  ++stencil;

  while (first != last)
  {
    if (!wrapped_pred(*stencil))
    {
      *result = *first;
      ++result;
    }
    ++first;
    ++stencil;
  }

  return result;
}

_CCCL_EXEC_CHECK_DISABLE
template <typename DerivedPolicy, typename InputIterator, typename OutputIterator, typename Predicate>
_CCCL_HOST_DEVICE OutputIterator remove_copy_if(
  sequential::execution_policy<DerivedPolicy>&,
  InputIterator first,
  InputIterator last,
  OutputIterator result,
  Predicate pred)
{
  // wrap pred
  thrust::detail::wrapped_function<Predicate, bool> wrapped_pred{pred};

  while (first != last)
  {
    if (!wrapped_pred(*first))
    {
      *result = *first;
      ++result;
    }

    ++first;
  }

  return result;
}

_CCCL_EXEC_CHECK_DISABLE
template <typename DerivedPolicy,
          typename InputIterator1,
          typename InputIterator2,
          typename OutputIterator,
          typename Predicate>
_CCCL_HOST_DEVICE OutputIterator remove_copy_if(
  sequential::execution_policy<DerivedPolicy>&,
  InputIterator1 first,
  InputIterator1 last,
  InputIterator2 stencil,
  OutputIterator result,
  Predicate pred)
{
  // wrap pred
  thrust::detail::wrapped_function<Predicate, bool> wrapped_pred{pred};

  while (first != last)
  {
    if (!wrapped_pred(*stencil))
    {
      *result = *first;
      ++result;
    }

    ++first;
    ++stencil;
  }

  return result;
}

} // end namespace sequential
} // end namespace detail
} // end namespace system
THRUST_NAMESPACE_END
